Billy had 75% fewer mochi balls than Ian. After Ian gave 250 mochi balls to Billy, Billy had ²₃ as many mochi balls as Ian. How many mochi balls did each of them have in the end?

1. Ian
2. Billy

	Billy	Ian	Total
Before	1x5 = 5 u	4x5 = 20 u	5x5 = 25 u
Change	+ 250	- 250
After	2x5 = 10 u	3x5 =  15 u	5x5 = 25 u

Number of mochi balls that Billy had at first in percentage
= 100% - 75%
= 25%

25% = ²⁵₁₀₀ = ¹₄

The total number of mochi balls at first and in the end remains unchanged. Make the total number of mochi balls the same. LCM of 5 and 5 is 25.

Number of mochi balls that Ian gave to Billy
= 20 u - 15 u
= 5 u

5 u = 250

1 u = 250 ÷ 5 = 50

Number of mochi balls that Billy had in the end
= 10 u
= 10 x 50
= 500

Number of mochi balls that Ian had in the end
= 15 u
= 15 x 50
= 750

Answer(s): (a) 500; (b) 750